When creating a dictionary in swift with array of strings as value as follows:
lazy var info : Dictionary = {
var dictionary = [String: [String]]()
dictionary["Key1"] = ["A", "B", "C"]
dictionary["Key2"] = ["D", "E", "F"]
return dictionary
}()
Cannot assign to immutable expression of type 'Value?'
Any ideas whats wrong here?
I've seen your own answer, which works, but there's a better way: use a Swift dictionary by declaring its proper type, in your case [String: [String]]:
lazy var info : [String: [String]] = {
var dictionary = [String: [String]]()
dictionary["Key1"] = ["A", "B", "C"]
dictionary["Key2"] = ["D", "E", "F"]
return dictionary
}()
Change
lazy var info : Dictionary = {
var dictionary = [String: [String]]()
dictionary["Key1"] = ["A", "B", "C"]
dictionary["Key2"] = ["D", "E", "F"]
return dictionary
}()
to
lazy var info : NSDictionary = {
var dictionary = [String: [String]]()
dictionary["Key1"] = ["A", "B", "C"]
dictionary["Key2"] = ["D", "E", "F"]
return dictionary
}()
and all is good :)
Related
I have the following array, I have to make sure to divide it in this way into subarray, taking into consideration the first part of the name followed by / as a criterion for subdivision, for example "name/other".
Can you give me a hand?
var a = ["origin/a", "origin/b", "origin/c", "remo/a", "remo/d", "remo/c", "next/g"]
var b = {
origin: ["a", "b", "c"],
remo: ["a", "d", "c"],
next: ["g"]
}
You could used reduce(into:_:) to do so:
let reduced = a.reduce(into: [String: [String]]()) { partialResult, currentTerm in
let components = currentTerm.components(separatedBy: "/")
guard components.count == 2 else { return }
partialResult[components[0]] = partialResult[components[0], default: [String]()] + [components[1]]
}
print(reduced)
Output:
$>["remo": ["a", "d", "c"], "next": ["g"], "origin": ["a", "b", "c"]]
One idea is like this:
First we need to separate the keys for the dictionary and all the values that need to be gathered together:
let keysValues = a
.map { $0.components(separatedBy: "/") }
.compactMap { components -> (String, String)? in
guard components.count == 2 else { return nil }
return (components.first!, components.last!)
}
Now we need to reduce that into a dictionary of [String: [String]] by grouping together the values for each key:
var dict: [String: [String]] = [:]
let answer = keysValues.reduce(into: dict) { (d, kv) in
let (k, v) = kv
d[k, default: []] += [v]
}
I can't find the best way to do this.
I have an array with 3 arrays in there(this never change)
var ancho = [String]()
var largo = [String]()
var cantidad = [String]()
var arrayDeCortes = [ancho,largo,cantidad]
arrayDeCortes = [[a,b,c,d,..],[e,f,g,h,..],[i,j,k,l,..]]
I need to get this:
[a,e,i]
[b,f,j]
[c,g,k]
[d,h,l]
My problem is that I don't know how many items there is in each array(ancho,largo,cantidad)
and how access to all of them.
I hope you understand me
You can use reduce(into:_:) function of Array like this:
let arrayDeCortes = [["a","b","c","d"],["e","f","g","h"],["i","j","k","l"]]
let arrays = arrayDeCortes.reduce(into: [[String]]()) { (result, array) in
array.enumerated().forEach {
if $0.offset < result.count {
result[$0.offset].append($0.element)
} else {
result.append([$0.element])
}
}
}
print(arrays)
// [["a", "e", "i"], ["b", "f", "j"], ["c", "g", "k"], ["d", "h", "l"]]
Edit: As #Alexander mentioned in the comments, there is a simpler way of achieving this by using zip(_:_:) function twice.
The following will return an array of tuples:
var widths = ["a","b","c","d"]
var heights = ["e","f","g","h"]
var quantities = ["i","j","k","l"]
let result = zip(widths, zip(heights, quantities)).map { width, pair in
(width, pair.0, pair.1)
}
print(result)
// [("a", "e", "i"), ("b", "f", "j"), ("c", "g", "k"), ("d", "h", "l")]
This question already has answers here:
Why is this array out of index?
(2 answers)
Closed 4 years ago.
I want to append elements from one 2D array to the another 2D array, but I get fatal error index out of bound.
the code is as follows:
var array = [["a", "b", "c"], ["d","e","f"],["g","h","i"]]
var array2 = [[String]]()
var x = array.count
var y = array[1].count
for j in 0..<x {
for i in 0..<y {
array2[j].append(array[j][i])
}
}
print(array2)
please don't tell me to just copy the array as this is not what I need, I am using this procedure to do something more complex than just copying an array.
Any suggestions as to why it goes out of bounds?
thanks
array2[j] doesn't exist as it's just an empty array.
It would be much easier to do this:
var array = [["a", "b", "c"], ["d","e","f"],["g","h","i"]]
var array2 = [[String]]()
for item in array {
array2.append(item)
}
print(array2)
[["a", "b", "c"], ["d", "e", "f"], ["g", "h", "i"]]
But that is just copying the array exactly. You should provide a more precise example of what you are trying to achieve.
Another option (Which makes your current code work) is to create a 'row' in the first loop ready for insertion:
var array = [["a", "b", "c"], ["d","e","f"],["g","h","i"]]
var array2 = [[String]]()
var x = array.count
var y = array[1].count
for j in 0..<x {
array2.append([String]())
for i in 0..<y {
array2[j].append(array[j][i])
}
}
print(array2)
Which gives the same output:
[["a", "b", "c"], ["d", "e", "f"], ["g", "h", "i"]]
It is going out of bounds because array2[0] doesn't exist. You need to create an an empty array there before appending to it. Then append that array to the outer array.
var array = [["a", "b", "c"], ["d","e","f"],["g","h","i"]]
var array2 = [[String]]()
for j in 0..<array.count {
var stringArray: [String] = []
for i in 0..<array[j].count {
stringArray.append(array[j][i])
}
array2.append(stringArray)
}
print(array2)
I have this special array var myArray : [Array<String>] = [["a"],["b"],["c"]]
I want to detect if "a" is already inside myArray
and after i would like to sort my array alphabetically but i havn't found any function to do all these things for my array
To find if your [[String]] contains "a", you can use contains twice:
var myArray : [Array<String>] = [["a"],["b"],["c"]]
if myArray.contains(where: { $0.contains("a") }) {
print("a found")
}
To sort the inner arrays, apply map to the outer array and sort each element:
var myArray : [Array<String>] = [["c", "a"], ["e", "b"], ["d"]]
let sorted = myArray.map { $0.sorted() }
print(sorted)
[["a", "c"], ["b", "e"], ["d"]]
I have this array :
var preferiti : [ModalHomeLine!] = []
I want to check if the array contains the same object.
if the object exists {
} else {
var addPrf = ModalHomeLine(titolo: nomeLinea, link: linkNumeroLinea, immagine : immagine, numero : titoloLinea)
preferiti.append(addPrf)
}
Swift has a generic contains function:
contains([1,2,3,4],0) -> false
contains([1,2,3,4],3) -> true
So it sounds like you want an array without duplicate objects. In cases like this, a set is what you want. Surprisingly, Swift doesn't have a set, so you can either create your own or use NSSet, which would look something like this:
let myset = NSMutableSet()
myset.addObject("a") // ["a"]
myset.addObject("b") // ["a", "b"]
myset.addObject("c") // ["a", "b", "c"]
myset.addObject("a") // ["a", "b", "c"] NOTE: this doesn't do anything because "a" is already in the set.
UPDATE:
Swift 1.2 added a set type! Now you can do something like
let mySet = Set<String>()
mySet.insert("a") // ["a"]
mySet.insert("b") // ["a", "b"]
mySet.insert("c") // ["a", "b", "c"]
mySet.insert("a") // ["a", "b", "c"] NOTE: this doesn't do anything because "a" is already in the set.